Die Photo

As well as a fairly large area for the die markings (And mask layer numbering.) Die code PW80Y that bears no relation to MAX1636.

In addition the die has a rather unusual marking. On the wide die seal (Conventionally tied to ground electrically) in one section the M1-M2 vias have been used to write CAEEFODS with a mirror image. Probably only 1 or 2 people have any idea what this was for 😉

Process

And elsewhere on the die are more unusual layout transistors with I guess greater current capability (Which scales with the emitter area).

Also on the die are lots of diffusion resistors

and the odd capacitor

Datasheet and Pin Out

There is a datasheet for the part. Switch Mode controllers are fairly complex circuits as can be seen from the block diagram in the datasheet.I’m not able to recognize any of the blocks but here is the pin out of the die

I don’t really know much about the ESD protection diodes. I know they evolved from simple reverse-connected diodes to quite sophisticated voltage clamp circuits. It looks like every company seems to do them differently. I have decapped enough parts now to see a variety of layouts, perhaps I should take a closer look at some of them.